Boosters
Timed items that shorten the AFK wait or multiply the AFK payout.
A booster changes the AFK reward, not the shop price and not kill shards.
Seconds multiplies the wait. 0.5 cuts it in half. 1 leaves it. Amount multiplies the payout. 2 doubles it. 1 leaves it. Hours is how long the effect lasts after the player uses the item.
The sample under Boosters in config.yml is Fast: 24 hours, half wait, same payout, a nether star named with &#E9D5FF.
/afk admin booster opens the list. You can edit hours, factors, material, name, lore, and glint, then save. /afk admin booster give <player> <id> <amount> hands out a saved booster. The id in the sample is Fast.
Using a booster while the same kind is already running extends the timer. The stored factors are what %afkplus_boost_seconds% and %afkplus_boost_amount% read. 1 means that part is idle.
Suggestions
Save a booster in the editor before /afk admin booster give, or the id will not exist. Check the live factor with %afkplus_boost_seconds% on the Placeholders page after a player uses one.