This will depend on the subreddit. If the subreddit doesn't state its guidelines or policy regarding posting your own content or reposts in its rules (see the subreddit's sidebar) or its subreddit wiki/FAQ, it's best to ask the mods of the subreddit first (through the 'Message the Moderators' link in the sidebar).
The Reddit FAQ has this to say about spam posts:
What constitutes spam?
It's a gray area, but some rules of thumb:
- It's not strictly forbidden to submit a link to a site that you own or otherwise benefit from in some way, but you should sort of consider
yourself on thin ice. So please pay careful attention to the rest of
these bullet points.
- If you spend more time submitting to reddit than reading it, you're almost certainly a spammer.
- If your contribution to reddit consists mostly of submitting links to a site(s) that you own or otherwise benefit from in some way, and
additionally if you do not participate in discussion, or reply to
peoples questions, regardless of how many upvotes your submissions
get, you are a spammer. If over 10% of your submissions are your own
site/content, you're almost certainly a spammer.
- If people
historically downvote your links or ones similar to yours, and you
feel the need to keep submitting them anyway, they're probably spam.
- If people historically upvote your links or ones like them -- and we're talking about real people here, not sockpuppets or people you
asked to go vote for you -- congratulations! It's almost certainly not
spam. But we're serious about the "not people you asked to go vote for
you" part.
- If nobody's submitted a link like yours before, give it a shot. But don't flood the new queue; submit one or two times and see what
happens.
To play it safe, write to the moderators of the community you'd like
to submit to. They'll probably appreciate the advance notice. They
might also set community-specific rules that supersede the ones above.
And that's okay -- that's the whole point of letting people create
their own reddit communities and define what's on topic and what's
spam.
The Reddiquette has this to say about posting your own content:
Feel free to post links to your own content (within reason). But if that's all you ever post, and it always seems to get voted down, take a good hard look in the mirror — you just might be a spammer. A widely used rule of thumb is the 9:1 ratio, i.e. only 1 out of every 10 of your submissions should be your own content.
