If you receive an error message or email notification stating your account exceeded storage quota, there's a few things you can do:
1. Upgrade to a higher plan, or contact firstname.lastname@example.org for a quote if you already are on the highest plan
2. Do some house-keeping on your feeds, by applying retention policies
If you already did house-keeping, note that this is a background operation and it may take a few minutes for storage quota to be updated to reflect this change.
Also note that storage quota applies to the feed and the subscription level (and on Enterprise plan, also on the user level).
This explains why you may see an error message when pushing to a feed that has only a few packages when you have other feeds in your account that - perhaps when combined - have reached or exceeded your quota.
You can always check your user profile on the MyGet web site, under the Subscription section, to find your current storage quota consumption percentage.
We highly recommend to use a package retention policy from the start to let MyGet do the house-keeping for you, and remember to pin those packages you want to survive any retention policies.